A variety of interchangeable groundworking apparatuses which are detachably mounted to self-propelled vehicles, such as skid steer front end loaders, are available on the market. As the interchangeability of these groundworking apparatuses provides a single host vehicle with the flexibility to perform a variety of different functions, these types of equipment are highly valued by contractors. This fact results because contractors who perform smaller jobs can utilize a single host vehicle and a variety of groundworking apparatuses to perform a multitude of operations rather than purchasing expensive dedicated machinery for each operation needed to be performed. One type of groundworking apparatus frequently utilized with a self propelled host vehicle is a rotary apparatus such as a cold pavement planer. A representative apparatus is model CP16 cold planar, available from Alitec Corporation of Brownsburg, Ind. This cold planer includes a rotating cylindrical drum or groundworking implement, which is sized to span less than the width of the skid steer loader to which the planar is detachably mounted. The drum is rotationally powered by a hydraulic motor, which utilizes pressurized fluid from a source on the self-propelled vehicle to produce the drum rotation.
A significant shortcoming of many types of rotary apparatuses relates to their inability to necessarily operate over regions in close proximity to obstructions lateral to the rotating drum. For example, planing operations are often necessary to be performed adjacent walls, high curbs, or around other fixed obstructions such as poles. To operate as close as possible to these types of obstructions, the rotating drum must be aligned such that its axis of rotation is perpendicular to the obstruction. In other words, the obstruction is laterally disposed to the ends of the cylindrical drum. During operation of the planar, larger horizontal clearances required between the end of the rotating drum and the obstruction translates to wider regions of unplaned material between the obstruction and the planed area. Previously, horizontal clearance problems relating to the sides of the vehicle have been addressed. A full side shift system taught in U.S. Pat. No. 5,203,615 discloses a rotary apparatus which is laterally shiftable between positions wherein the rotating drum extends beyond either side of the self propelled vehicle. However, while a rotary apparatus can now be extended beyond either side of the vehicle, another clearance problem pertaining to the hydraulic motor which powers the rotation of the apparatus still exists. As disclosed in U.S. Pat. No. 5,203,615, as well as in U.S. Pat. No. 4,878,713, this hydraulic motor typically extends laterally from the drum. As a result, when an operator utilizing a full side shift system laterally shifts the rotary apparatus to plane beyond the same side of the vehicle on which the apparatus motor is disposed, the rotating drum can usually approach the lateral obstruction no closer than approximately the lateral extent of the motor. A closer planing operation can typically be performed by turning the self-propelled vehicle around, laterally shifting the rotary device to the opposite vehicle side, and repeating the planing operation around the obstruction. However, in addition to being highly inconvenient and impossible in certain situations, such a repetitious task is time consuming and therefore costly to a contractor. Therefore, it is highly desireable to provide a rotary apparatus wherein the drive system which powers the spinning drum does not require additional clearance on either side of the drum, thereby facilitating its functioning around obstructions.
Another disadvantage of a rotary apparatus having a motor extending laterally therefrom relates to vertical clearances. For such apparatus constructions, difficulties may be encountered in lowering the rotating drum into a hollow or during use adjacent a stepped incline, such as a curb. For example, when asphalt near a curb is being planed, the hydraulic motor may at first extend unobstructed over the curb. Neither horizontal nor vertical clearance problems for the motor initially exist. As the planing operation progresses and a deeper cut in the asphalt is desired, the drum must be lowered. However, because the hydraulic motor may contact the top of the curb, vertical clearance problems with the motor may prevent further planing. Vertical clearance problems are most serious when a single, large diameter motor, disposed on the outside of the rotating drum, is used to provide the necessary torque instead of two smaller diameter motors, one disposed on either side of the drum.
Rotary devices disposed on dedicated machines, i.e. machines designed primarily for a certain function, have previously utilized hydraulic motors which are either recessed within the sides of the rotary apparatus or located within the rotary apparatus itself. While a construction which recesses the motors reduces the vertical and horizontal motor clearance difficulties described above, this construction suffers from different shortcomings. Specifically, when small motors are disposed on either end of the rotating drum, a pair of hydraulic lines to each motor is presently necessary to provide fluid communication with the pressure source. The presence of independent pairs of hydraulic lines between each motor and the hydraulic pressure source is undesirable for several reasons. First, the large number of lines on the machines provides greater opportunity for mechanical or material failure. Second, the complexity of the connection and disconnection of the hydraulic motors from the hydraulic pressure source is increased. Third, depending on the orientation of the pair of hydraulic lines from each motor, some vertical clearance problems may result. Internally mounted rotary apparatus dual drive systems heretofore taught also suffer from a similar deficiency. Because the hydraulic fluid inlet and outlet lines are disposed on the same side of the drum, vertical clearance problems are also possible.
Another problem with many rotary apparatuses relates to the difficulties of replacing the rotating drum or groundworking implement with an alternate drum. As different planing jobs are best performed with specially designed groundworking implements, operators of rotary apparatuses are constantly having to replace the rotating groundworking implement. For instance, some groundworking implements employ pick structures suited to best plane concrete, while others employ pick structures suited to best plane asphalt. In addition to groundworking implements being specially designed for the material which is being operated over, special tasks require groundworking implements with specially designed pick patterns. For example, one groundworking implement pick pattern only extends six inches along the length of the groundworking implement and is used to plane along cracks to allow for crack repair.
Because of the position and design of the mechanical connections between many prior art groundworking implements and their support structures, disconnection therefrom is labor intensive, highly inconvenient, and time consuming and therefore expensive. For example, in order to disengage the rotating work implement from its protective housing in most cold planer apparatuses, an operator must remove a number of fasteners disposed within the housing itself. An operator must therefore be sufficiently flexible and dexterous to maneuver herself such that she can insert her hands and arms between the inside of the housing and the end of the work implement to work the fasteners. Moreover, because the environment inside the protective housing is likely corrosive due to the basic composition of some materials being planed, the fasteners are likely to corrode and be even more difficult to remove.
The rotational powering of most cold planer groundworking implements also adversely affects the simplicity of detaching the implement from its support structure. Many devices use a gear box attached inside the work implement and rotatable therewith. A motor from outside the protective housing powers the gear box, which converts the input motor shaft rotation into a desirable rate of revolution for the groundworking implement. To remove the work implement, however, requires removal of the motor from engagement with the gear box. This removal is highly undesirable for a variety of reasons. For example, the gasket between the parts is prone to being ripped during removal, and repair is both costly and time consuming. Another major problem is the high likelihood of contamination of the gear box which can quickly lead to its damage or destruction. Work implements are typically changed on construction sites which are notoriously dirty and dusty. When the motor is removed from the apparatus, the shaft is oily and contaminants therefore attach to the shaft. Unless the operator remembers to diligently clean the motor shaft, its insertion into the apparatus gear box, which has been mounted in the next groundworking implement, introduces the contaminants into the gear box. Moreover, oil is likely to spill out. Also, many devices use a single motor in conjunction with a gear box which is cantilevered on one side of the rotating groundworking implement. This orientation puts significant strain on the support bearings, which therefore damage relatively easily and require more frequent replacement.